We present a kinematic study of the nuclear stellar disk in M31 at infrared wavelengths using high spatial resolution integral field spectroscopy .
The spatial resolution achieved , FWHM = 0 \farcs 12 ( 0.45 pc at the distance of M31 ) , has only previously been equaled in spectroscopic studies by space-based long-slit observations .
Using adaptive optics-corrected integral field spectroscopy from the OSIRIS instrument at the W. M. Keck Observatory , we map the line-of-sight kinematics over the entire old stellar eccentric disk orbiting the supermassive black hole ( SMBH ) at a distance of r < 4 pc .
The peak velocity dispersion is 381 \pm 55 km s ^ { -1 } , offset by 0 \farcs 13 \pm 0 \farcs 03 from the SMBH , consistent with previous high-resolution long-slit observations .
There is a lack of near-infrared ( NIR ) emission at the position of the SMBH and young nuclear cluster , suggesting a spatial separation between the young and old stellar populations within the nucleus .
We compare the observed kinematics with dynamical models from \citet peiris2003eccentric-disk .
The best-fit disk orientation to the NIR flux is [ \theta _ { l } , \theta _ { i } , \theta _ { a } ] = [ - 33 ^ { \circ } \pm 4 ^ { \circ } , 44 ^ { \circ } \pm 2 ^ { \circ } , - 15 ^ { \circ } \pm 15 ^ { \circ } ] , which is tilted with respect to both the larger-scale galactic disk and the best-fit orientation derived from optical observations .
The precession rate of the old disk is \Omega _ { P } = 0.0 \pm 3.9 km s ^ { -1 } pc ^ { -1 } , lower than the majority of previous observations .
This slow precession rate suggests that stellar winds from the disk will collide and shock , driving rapid gas inflows and fueling an episodic central starburst as suggested in \citet chang2007the-origin .